Hedderwick: Marine Architecture (1830)

MARINE ARCHITECTURE,

PART II.

CHAPTER I.

Coppering.-- When a vessel is to be copper-sheathed, the bottom
should be dressed very smooth, and all the projecting parts neatly rounded
off. In several parts of Britain, it is the custom to plane the bottom, which
takes off all the protuberances left by the roundness of the adze. This is an
excellent plan, and makes the copper lie close to the plank, and have a very
smooth surface.

Before commencing with the coppering, the ship should be all properly
caulked, the seams paid over with pitch, and also all the rough pitch scraped
off the edges of the seams, which are then to be filled up level with the
surface of the plank. This is sometimes
done by driving a thread of oakum in the mouth of the seam, but more
frequently by nailing in a thread of spun yarn. After this, the bottom must be
paid over with tar boiled with a little pitch to a gluey consistency,
considerably softer than what is commonly used for paying the seams. The paper
must now be prepared, by being dipt in the warm tar and pitch, and left to dry
for a few days before it is used. The copper must be pierced before it is
brought to the ship, except what sheets may be required for the upper parts
and ends of the vessel, which have to be cut suitable to the place where they
are to be nailed on, and fillings up where square-sheets are not wanted.

The copper sheets are commonly about 4 feet long, and 12 or 14 inches in
breadth, covering each about 4 feet of surface of the ship's bottom when
nailed on. The thickness of the copper is denominated by the weight per square
foot; the lightest used is 16 ounces per square foot, and running up to about
28, and sometimes to 32 ounces per square foot, which is the heaviest. The
size for merchant vessels is commonly 24-ounce copper for the luff of the bow
and bilges, and 18 or 20 ounces for the rest of the bottom, except a breadth
or two along about the load-water mark at midships (which is apt to be rubbed
by boats or fenders) which is put on of 24 or 28 ounce.

Sometimes the whole of the copper on the fore-body of the ship is 4 or 6
ounces heavier than on the after-body, it being found to wear faster on the
former than the latter part of the ship, by the reaction of the fluid when
sailing. The piercing of the copper is commonly done by hand, with a short
small-pointed punch made to the exact size of the nails, with a shoulder or
stop to prevent it going too far through.

The place of the nails on the sheet is marked off with a chalk line, after
this manner: Strike a line all round the edges of the sheet, 5-8ths or 3-4ths
of an inch within. Between the side-lines, divide the breadth into three or
four equal parts; strike the chalk-line along the sheet on these divisions,
thus making a line for two or three row of nails along the middle of the
sheet. It is next divided the other way, by setting, from the line across the
end, distances equal to what the lines along the sheet are apart; then strike
lines across the sheet at these equal distances, which will divide it into
squares of three or four inches, at the intersections of which the holes for
the nails are to be punched; and on the line at the edge, and one end of the
sheet, an additional hole between every cross-line, making the distances
between them 1½ inch, which is the farthest they should be apart. All
the middle holes are pierced one edge and one end, the other edge and end
being pierced after the sheet is put on. This first sheet is called the
pattern-sheet, all the others being done in the same manner.

Having the pattern-sheet thus lined out, lay a sheet upon a hard block of
wood having an even smooth surface; place the pattern-sheet exactly over it,
fasten them both to the block with two or three nails, then punch the lower
sheet through the pattern; and thus you may continue punching, using the
pattern-sheet for a considerable time until the holes in it appear to widen,
when it will be necessary to change it, and use another for that purpose.

It must also be observed, that the copper punched through this
pattern-sheet is only for one side of the vessel; and that required for the
other side must have the end-holes in the opposite end of the sheets.

The paper and copper being thus prepared, the paper is put upon the
vessel's bottom with small tacks or scupper nails. In commencing with the
copper, it makes the most regular work to begin at the upper part of the
bottom amidships, and work from that towards both ends of the ship, carrying
the edge as fair as possible, and giving the after end of every sheet one inch
of overlap over the fore end of the other, at the same time taking particular
care that each sheet lie quite flat to the plank. In nailing, always begin in
the middle of the sheet, and complete the two or three middle rows, beating
the copper completely up before you commence nailing the edges, otherwise it
will bag off between the nails.

When you approach towards the ends of the vessel, the sheets will begin to
rise at their fore and after ends; therefore their upper edges must be gored
or cut off to the proper height till such time as they are diminished to
1½ inch in breadth. When this first strake is completed, begin with the
next under, placing the end of the beginning sheet right under the middle of
the one above, and its upper edge, so as to cover one inch of the lower edge
of the sheets above. When a number of sheets are tacked on, begin and nail
them first in the middle; work them close up to the plank; punch the lower
edge of the sheets above through the holes in the upper edge of the sheet
below, and the fore end of the sheet abaft each; after they are all properly
nailed, they must be beat perfectly smooth with a mallet. When you come to the
stem, take care to ply the copper neatly into the hoods, not regarding how the
edges of the sheets may appear to run, provided they are close fitted to the
plank. When they are all nailed to the sides of the stem, its fore part, and
two or three inches round each side, must be coverted with sheet-lead of from
1-4th to 3-8ths of an inch thick, and properly fastened with copper nails a
little stouter than those used for nailing the copper. Supposing several
strakes got round, continue to work downwards till you come to the bilge, and
then work from the keel upwards; fix the sheets first to the sides of the keel
with a few nails, to keep them to their proper place; then work them neatly
into the corner of the rabbet, and drive the nails close to it; ply the sheets
close to the keel and bottom plank or garboard-strake; turn up the edges of
the copper or lead which is under the keel, and nail it over the lower edge of
the copper on the side of keel; continue to work outwards towards the bilge,
making the outer or upper edges overlap the under edges of the next succeeding
strake right fore-and-aft. When you come near to the bilge-planks, where the
size of the copper is altered, fill up the goring or narrow ends forward with
the strong copper as well as that on the bilge amidships; but the gorings on
the after-runs is the same size of copper as on the other parts of the bottom.
In coppering the stern-post and rudder, if sheet copper is not put under the
straps of the braces and pintles, you must be very careful to put it neatly
round them, and set close to all their edges with a caulking-iron; the copper
must also be nailed quite close to the back of the stern-post, otherwise it
will soon be chafed off; also be very particular how you fit the copper into
the end of the keel. The bottom sheet on it and the lower end of the rudder
should be very strong copper. On the other parts of the rudder, the copper may
be of the common thickness.

Peter Hedderwick: A Treatise on Marine Architecture, containing the theory and practice of shipbuilding, with rules for the proportions of masts, rigging, weight of anchors, &c including Practical Geometry and the Principles of Mechanics; observations on the Strength of Materials, Hydrostatics, &c. with many valuable tables calculated for the use of shipwrights and seamen; also the proportions, scantlings, construction, and propelling power of steam-ships. Illustrated with twenty large plates, containing plans and draughts of merchant-vessels from fifty to five hundred tons, with mast and rigging plans; plans and sections of a steam-boat of eighty-horse power; and eight quarto plates of diagrams, &c., by Peter Hedderwick.Printed for the Author, Edinburgh, 1830. pp 329-331.